AudioCodes Mediant 600 - Adding SIP Record-Route Header to SIP INVITE; Replacing Contact Header for SIP Messages

SIP User's Manual 406 Document #: LTRT-83310
Mediant 600 & Mediant 1000
19.2.5.6 Adding SIP Record-Route Header to SIP INVITE
You can configure SAS to add the SIP Record-Route header to SIP requests (e.g. INVITE)
received from enterprise UAs. SAS then sends the request with this header to the proxy.
The Record-Route header includes the IP address of the SAS application. This ensures
that future requests in the SIP dialog session from the proxy to the UAs are routed through
the SAS application. If not configured, future request within the dialog from the proxy are
sent directly to the UAs (and do not traverse SAS). When this feature is enabled, the SIP
Record-Route header includes the URI "lr" parameter, indicating loose routing, as shown in
the following example:
Record-Route: <sip:server10.biloxi.com;lr>
Notes:
• This feature is applicable only to SAS outbound mode.
• This feature can also be enabled using the SASEnableRecordRoute ini
file parameter.
 To enable the Record-Route header:
1. Open the SAS Configuration page (Configuration tab > VoIP menu > SAS > Stand
Alone Survivability).
2. From the ‘Enable Record-Route' drop-down list, select Enable.
3. Click Submit to apply your changes.
19.2.5.7 Replacing Contact Header for SIP Messages
You can configure SAS to change the SIP Contact header so that it points to the SAS host.
Therefore, this ensures that in the message, the top-most SIP Via header and the Contact
header point to the same host.
Notes:
• This feature is applicable only to SAS outbound mode.
• The device may become overloaded if this feature is enabled, as all
incoming SIP dialog requests traverse the SAS application.
Currently, this feature can only be configured using the SASEnableContactReplace ini file
parameter.

[0] (default): Disable - when relaying requests, SAS adds a new Via header (with the
IP address of the SAS application) as the top-most Via header and retains the original
Contact header. Thus, the top-most Via header and the Contact header point to
different hosts.

[1]: Enable - SAS changes the Contact header so that it points to the SAS host and
therefore, the top-most Via header and the Contact header point to the same host.